Project Summary/Abstract: Environmental events can rapidly alter the expression of genes in the cerebral cortex. However, what those changes are, and how they may alter the functional adaptation of neuronal circuits and animal behavior, remains poorly understood. The current proposal seeks to identify the regional and cell-type specific changes in neuronal gene expression induced in the frontal cortex by an acute environmental stimulus, and how this influences behavior. Preliminary results from the PI?s laboratory during the prior funding period revealed the novel finding that the acute environmental stimulus of sleep deprivation rapidly upregulates serotonin 2A receptor (5-HT{2A}R) levels in the frontal cortex of mice, in a manner that requires function of the immediate early gene transcription factor Egr3. The overall goal of the current proposal is to define the cell-type specific transcriptional response of frontal cortex neurons to the acute environmental stimulus of sleep deprivation, and to determine the role of activity dependent gene expression in specific frontal cortex circuits on behavior. In this application, the research group brings together an interdisciplinary team and takes an integrated approach combining molecular, cellular, and behavioral approaches to accomplish the goal. In Aim 1 single cell RNA-seq will be employed to define the cell-type specific changes in gene expression induced in frontal cortex neurons by the acute environmental stimulus of sleep deprivation. Parallel studies performed in Egr3-/- mice will identify the environmentally-induced gene expression changes that require this activity-dependent immediate early gene transcription factor. In Aim 2, excitatory and inhibitory optogenetic methods will be employed to determine the role of specific cortical circuits in regulating both the 5-HT{2A}R-dependent behaviors identified during the previous funding period, and prefrontal cortex dependent spatial working memory behavior. Impact: It is anticipated that successful completion of these studies will elucidate mechanisms by which environmental stimuli rapidly alter cell-type specific gene expression in the cortex, and how this impacts specific receptors and circuits to alter frontal cortex-mediated states of alertness and processes of spatial memory formation.